s8 6 
Messrs. Allen and Pepys on the 
a residuum of 2 parts in 100, and we began with 49,84 cubic 
inches. The tray, with its contents, being placed in the platina 
tube, was heated to redness for a quarter of an hour, and the 
gas made to pass over it several times. When all was cool, 
the original quantity was neither increased nor diminished, 
and on withdrawing the tray we found only ,2 of a grain of 
oxide of iron ; so that this specimen of plumbago contains 
only 5 per cent, oxide of iron. 
The gas being now examined. 
Lime water absorbed 55 parts from 100 
The tests for oxygene 42 
Residuum - - 3 or an increase of 1 per cent. 
100 
Correction for Temperature. 
6o° 0,103 49*84 
44 ^ 1,64 
16 did’. 3,648 add for temp. 51,48 
Correction for Pressure. 
30: 29,94: : 51 ,48 -. 51,37. 
The quantity of oxygene at the mean would be 51,37 cubic 
inches. 
100 : 55 : : 51,37: 28,25. 
Therefore 28,25 cubic inches of carbonic acid gas were pro- 
duced. 
300 : 47,26, : : 28,25 : 13,35 grains. 
13,35 '• 3> 8 : : 100 '• 28,46. 
Then, according to this experiment, 100 grains of carbonic 
acid contain 28,46 of the carbonaceous part of the plumbago. 
